The state’s much-debated map of marine protected areas for Southern California will take effect Oct. 1, the Fish and Game Commission determined Wednesday in a 4-1 vote during a meeting in Stockton.

The size and shape of the marine parks had been approved by the commission in December without a definite start date for implementation. The expanded reserves include sites offshore of La Jolla, Imperial Beach, Point Loma and many other spots where fishing is essentially off-limits.

The Department of Fish and Game plans to step up public outreach in coming months to help residents know where the lines are.

“We’re working on signage, and will provide information in a booklet and on the website ... and make efforts to reach out to the media outlets in the region as the date approaches,” said Jordan Traverso, a spokeswoman for the state Department of Fish and Game.

She said agency staff members routinely attend sport fishing shows to educate anglers about protected areas and said game wardens “make countless contacts in the field that aren’t always for violations, but rather education, and they will continue to do so.”

Fishing groups largely opposed expansion of the reserves and some wanted the start date pushed into 2012. Many anglers felt the process was rigged and doubt that it will markedly improve the nearshore ecosystem.

Conservationists praised Wednesday’s decision, citing several recent studies about the need to protect marine waters from overfishing, pollution, climate change and other threats.

“Southern California’s quality of life — and many of its jobs and businesses — rely on our coast and ocean. These protections cannot come soon enough,” said Kaitilin Gaffney of Ocean Conservancy.

Developed under the Marine Life Protection Act of 1999, the network of 49 MPAs and three special closures covers approximately 354 square miles of state waters in Southern California and represents approximately 15 percent of the region.